Industrial application of test-based updating procedures for structural dynamics FE-models

This paper covers the correlation analysis, the sensitivity analysis and the final FE model updating performed upon completion of the FE normal modes analysis and the experimental modal analysis. The main object of the structural dynamics analysis is the body structure of a new lightweight troop transportation vehicle, featuring a newly designed multilayer metal skin. The size and the type of structure results in a very limited set of true global modes: most modal deformation patterns are characterized by a superposition of spatially well-separated local dynamic phenomena. From correlation analysis it was found that the multilayer skin shows pronounced non-isotropic dynamic behavior. In order to tune the structural dynamics FE modeling in these conditions, an effective approach is used to avoid re-evaluation of the full-size FE-model with every iteration. Thereto, specific parts are isolated from the original model and analyzed in simple boundary conditions. Target frequencies for updating equations are set by offsetting the experimental resonance frequencies extracted from the global experimental modal analysis. This approach led to improved modeling of the structural anisotropy. The maximum frequency deviations between FEA and experimental modes are reduced with 30%, while the number of correlated modeshapes has substantially increased.